Hollow engraving points, holders and cleaning device for engraving coated sheets



HOLLOW ENGRAVING iOINTS, HOLDERS AND.CLEANING DEVICE FOR ENGRAVING COATED SHEETS Nov. 21, 1967 R H.S|K|-G ETAL 3,353,273

Filed June 15, 1966 5 Sheets-Sheet l Nqv. 21', 19 67 R H. SICKING ETAL HOLLOW ENGRAVING iOINTS, HOLDERS AND CLEANING DEVICE FOR ENGRAVING COATED SHEETS Filed June 13, 1966 a Sheets-Sheet 2 United States Patent Ofl ice 3,353,273 Patented Nov. 21, 1967 3,353,273 HOLLOW ENGRAVING POINTS, HOLDERS AND CLEANING DEVICE FOR ENGRAVING COATED SHEETS Robert H. Sicking, 5705 Itaska St, and Robert H. Sovar, 2552 Redman, both of St. Louis, Mo. 63136 Filed June 13, 1966, Ser. No. 557,865 7 Claims. (Cl. 33-18) ABSTRACT OF THE DISCLOSURE An elongated engraving stylus point holder body formed with a central suction passage therein opening downwardly, and connected at its upper end through a lateral passage to a flexible suction conduit to a suction device or pump. The stylus point holder has a stylus point receiving collet chuck at its lower end formed with a concentric central stylus point receiving bore therein which opens upwardly in communication with the lower end of the first mentioned central suction passage. A hollow elongated stylus engraving point is removably seated in said bore and retained therein by the collet chuck. The hollow stylus engraving point is formed with a conical scribing .point at its lower end, with a restricted (small) suction inlet passage extending upwardly through the center of the conical scribing point into communication with a larger central suction conduit that extends axially upwardly through the hollow stylus engraving point with the upper end of this larger central suction conduit opening in free suction communication with the lower end of said central suction passage in the point holder body.

A vacuum jacket is removably mounted on and surrounds the point holder body, extending downwardly thereon and then tapering inwardly to surround the lower end of the body and the collet chuck, terminating in closely encircling concentric relation to and lightly above the scribing tip of the stylus .point. The vacuum jacket has a lateral suction passage therethrough in communication at its inner end with upper end of the central suction passage of the body, and at its outer end adapted to be connected in communication with the flexible suction conduit.

The pointer holder body has downwardly and outwardly inclined suction conduits in communication at their upper ends with the central suction passage of the body, and at their lower ends in communication above the collet chuck with the space between the collet chuck and the interior of the vacuum jacket, located materially above the tapered engraving point of the stylus.

The invention described herein may be manufactured and used by or for the United States Government for governmental purposes Without the payment to us of any royalty thereon.

This invention relates to the engraving art, and more particularly to tools used in the engraving of coated transparent sheets.

Recent developments in producing contour maps, weather maps, engineering drawings, circuit master negatives, and the like involve scribing or engraving the negatives or coated transparent sheets. The material, for instance, forming the negative may resemble a photographic negative after development in that it is a transparent body or sheet which carries an opaque coating on its surface. The body of the negative may be glass, but is usually made of transparent and flexible plastic film which is covered on one side with a photographically opaque coating having the proper physical characteristics. Such films and coating materials suitable to be scribed or engraved are now well known in the art, commercially available, and therefore will not be further described in detail.

The actual or final negative is prepared on the above described coated base by selectively removing a portion of the opaque coating material. When a negative, having been so prepared, is placed in rays emitting from an illuminating light source, the light rays will pass through the negative in those areas or lines where the coating has been removed and will be blocked in those areas which remain coated with the opaque coating material.

Portions of the opaque coating are removed by various instruments, each designed for a specific purpose. Several common forms of scribing instruments terminate in conical scribing points for scribing fine lines, others in blade points for scribing wider lines. Scribing instruments may be further classified into tracking scribers and rigid and non-tracking scribers. For instance, a tracking scriber would be one in which two conical points are mounted side by side and swiveled to a movable support, usually manually movable, to produce two parallel lines such as to indicate a road highway on a map. An example of a rigid scriber would be one which rigidly supports a conical scribed or stylus point capable of scribing equally well in all directions of movement of its relatively rigid supporting member.

This invention has its primary application on rigid scribers using conical points.

Examples and description of such a scriber are disclosed in our co-pending application, Ser. No. 384,049, filed July 17, 1964, entitled, Hollow Engraving Point and Holder for Engraving Coated Transparent Sheets, in which the inventors are R. H. Sovar and R. H. Sicking.

The present invention pertains to the scriber or stylus holder, and the scribing point, and not in the apparatus for moving the holder and point, for instance, selectively or relatively along perpendicular X and Y coordinates. One example (not shown) comprises a holder in a support of the so-called rigid scriber apparatus in which the coated transparent sheet is moved in one direction under the stylus point, for instance, at variable rates while the holder and its stylus point are moved at various controlled rates in a direction perpendicular to the direction of movement of the opaque coated transparent sheet, as might be contemplated in FIG. 1 of our aforementioned copending patent application. These engraving machines are commercially well known in the art and the relative movement of the support for the scribing point holder and relative perpendicular movement of the coated sheet are often controlled by electronic computers under the control of punched tapes although manual control means are sometimes employed.

An object of this invention, however, is an improvement, or improvements, in the scribing point or stylus and its holder.

A further object is provision of a hollow scribing point and holder which is adapted to remove andeliminate the opaque coating material which is displaced from the plastic or other transparent base by the hollow scribing or engraving point or stylus.

A further object of the invention is the provision of a self-cleaning stylus and holder, including calibrated sprin-g adjusting meansfor regulating the scribing or cutting pressure of the stylus point'on an opaque coated transparent sheet or base.

A further object is the provision of a hollow scribing point or stylus and holder, including means for applying suction to the interior of the stylus point to withdraw coating debris displaced by the stylus through the interior thereof to prevent the accumulation thereof in or around I the contacting or cutting end of the scribing point.

A further object includes a collet chuck in the tool holder for removing and replacing the hollow stylus points and a removable hood enclosure or shroud surrounding the chuck unit in predetermined closely spaced relation to the outer or scribing end of the stylus and in predetermined closely spaced relation above the level of the scribing end of the stylus with the interior of the hood in communication with a vacuum or suction source to withdraw any coating debris removed by the stylus which is displaced by the cutting end of the stylus.

A further object is the provision of a hollow stylus holder and removable hollow cutting stylus with vacuum or suction means connected in communication with the interior of the holder, including spring means within the holder for urging the stylus into scribing relation with an opaque coating, including means carried by the holder for varying the scribing or engraving pressure on the opaque coating.

A further object is the provision of a hollow scribing point or stylus and a stylus holder which has a concentric cylindrical bore extending upwardly therethrough from the stylus 'point to receive opaque coating debris or plugs therein, and a cylindrical plunger fitting the bore with the lower end thereof normally projecting outward slightly beyond the lower end of the stylus point, together with light spring means within the stylus impinging the upper end of the plunger, whereby the plunger is moved upward by contact of the stylus point with the opaque coating and collection of plugs or debris displaced by the point entering the lower end of the bore during the scribing operation, in which the spring means projects the plunger downward to displace the coating debris or plugs from the interior of the bore when the stylus is raised above the opaque coating of the transparent sheet, including means for applying suction in surrounding relation to the point to remove the debris displaced by the plunger when the stylus is raised off the coated sheet.

Other objects and advantages of the invention will become apparent from the following description and accompanying drawings in which like reference characters refer to like parts in the several figures.

Drawings FIGURE 1 is a vertical longitudinal sectional view, partly in elevation, illustrating one form of the invention, and showing the movable scriber supporting means of the plotter partly broken away.

FIGURE 2 is an enlarged detail longitudinal sectional view through the hollow automatic clearing or cleaning scribing point and chuck means seen in elevation in FIG. 1, but removed from the plunger.

FIGURE 3 is an exploded view, in section, of the hollow engraving or scribing point, chuck means, and surrounding jacket shown in FIG. 2.

' FIGURE 4 is a side elevation of a slightly modified form of hollow stylus point self-cleaning scribing member and holder, parts being broken away and shown in section to show the interior thereof, the mounting means therefor from the scribing machine or plotter being shown in dotted lines.

FIGURE 5 is an enlarged detail longitudinal sectional view of the scribing tip unit shown in FIG. 4, a portion of the supporting tube and plunger member being shown in dotted lines.

FIGURE 6 is a further slight modification, with the scribing tip unit shown in FIGS. 1 to 4 shown in elevation with the upper portion of the barrel and plunger broken away and shown in section to illustrate a calibrated spring tensioning or adjusting means for precision regulation of the scribing point position and scribing or engraving pressure.

FIGURE 7 is an enlarged fragmentary modified detail view of the upper portion of a hollow point self-cleaning scribing member such as shown in FIG. 4, parts heing broken away and shown in section, illustrating an auxiliary means for regulating or changing the spring tension on the scribing tip, together with the spring tension adjustment means shown in FIG. 4, utilizing calibrated inserts.

FIGURES 8, 9 and 10 are detail perspective views respectively, of different sleeve-like inserts which are calibrated in lengths to provide variations in spring pressure on the scribing point in excess of that possible with the screw threaded spring pressure adjustment screw or thinrble.

FIGURE 11 is an enlarged detail longitudinal sectional view through the removable hollow scribing point shown in FIGS. 2 and 3, as employed in the construction illustrated in FIGS. 1 and 4 to 7.

FIGURE 12 is an enlarged detail view of a modified form of self-clearing scribing or automatic self-purging point which may be chucked in a standard scribing apparatus, and may also be chucked in the scribing point holding chuck portion shown in the preceding FIGS. 1 to 6, if desired.

Referring more particularly to FIGS. 1 to 3, the reference numeral 1 denotes a portion of a so-called rigid type support member with the plunger axis located at the intersecting X and Y coordinate axes of a remote controlled plotter in which the support member 1 is selectively moved relative to the opaque coated transparent sheet indicated at 2. The sheet 2 comprises a lower transparent sheet with an upper opaque coating to be engraved or scribed.

The coated sheet 2 may be disposed in a plane under the support member 1 and selectively moved, prefenbly by a computer, in two directions at right angles to each other to shift the support member 1 and the scribing means, indicated generally at 3, in any direction along and across the coated sheet 2 during the scribing operation from any selected position or point on the coated sheet. Alternatively, the support member 1 and scribing point 4 are moved in one direction only, for instance to difierent positions or points across the coated sheet 2 while the opaque coated sheet 2 is selectively moved in transverse directions to the movement of the scribing point 4; resulting, of course, with the relative shifting of the scribing point 4 from any selected point on the opaque coated sheet 2 to any other selected point on the sheet. If the scribing or engraving point 4 during such movement is in scribing contact with the sheet, the coating will be removed to engrave a line or curve, as the case may be, as set forth and contemplated in our aforementioned copending patent application Ser. No. 384,049.

The reference numeral 5 denotes a shouldered cylindrical adapter sleeve or tool holder which is inserted in a complementary bore 6 in the support 1 and retained in position by the. set screw 7. The sleeve 5 has a concentric cylindrical bore 8 for receiving the scribing tool holder or assembly 9, which is held in position in the adapter sleeve 5 by a set screw 10, and may be adjustable to dispose the scribing point 4 and actuating solenoid 11 in the desired scribing relation to the opaque coated sheet 2.

As seen in FIG. 1, the scribing tool holder 9 has a cylindrical guide passage 9a to receive the scribing plunger 12. The holder 9 is counter-bored at 13 to receive the return or lifting spring 14 for the plunger 12. The upper end of the scribing tool holder or assembly 9 carries an actuating solenoid 11 which, when energized by the conductors 15, produces downward movement of the solenoid plunger rod 16, as seen in FIG. 1. The plunger rod 16 forces the bifurcated end 17 downward to compress the light pressure spring 18 to exert downward scribing pressure on the plunger 12. The plunger 12 depresses the scribing point 4 in scribing contact with the opaque coated sheet 2.

When the solenoid 11 is deenergized, the return spring 5 14, through the pin and slot connection 19, lifts the plunger 12 to raise the scribing point 4 off the sheet 2.

The lower end of the plunger 12 is provided with a threaded socket 20 to receive the scribing point holder or scribing means, indicated generally at 3, constituting the invention. The scribing means 3 comprises a chuck body, or point holder 21, having an upper threaded end 22 for securing the scribing point holder 3 in the socket 243 of the plunger 12, as best seen in FIGS. 2 and 3.

The body 21 is formed with a threaded smaller diameter lower end forming a collet chuck 23 of substantially conventional design with a central bore 24 split longitudinally to receive the cylindrical body 25 of the scribing point or stylus 4. A threaded collet collar or sleeve 26 is provided for tightening the chuck 23 to hold the point 25 securely in the chuck, as seen in FIG. 2.

The body 21 is formed with a central suction passage 27 and lateral suction passages 27a inclining upwardly and inwardly from the bottom of the body 21. These passages 27 and 27a open at their upper ends into an enlarged lateral suction conduit 28, as shown.

The lower end of the scribing point 4 has a central suction passage 29 extending upwardly through the scribing point, as seen in FIG. 11, which opens upwardly into a larger concentric suction passage 30 in the body 25. The passage 30 is disposed or adapted to be disposed in communication with the central suction conduit 27, and is formed with lateral suction inlets or vents 31 which extend from the exterior of the scribing body 26 adjacent the conical scribing end and above central passage 29 into the bore 33.

The body portion 21 of the point holder is cylindrical and a vacuum jacket or sleeve 32 is provided having an upper cylindrical bore 33 which slidably fits the body 21 and is formed with a suction outlet 34 in one side thereof. Suction outlet 34 is disposed in register with the outlet 28 in the body 21 when the sleeve 32 is in place on the body portion 21 as shown. The sleeve 32 is provided with a slot or notch 35 to receive a pin 36 projecting from the body 21 to align the suction passages 28 and 34. The body 21 is provided with 0 rings 37 seated in annular channels 33. The 0 rings 37 prevent suction leakage between the body 21 and sleeve 32 and comprise friction means for retaining the sleeve or jacket 32 in place on the body 21. The pin 36 may limit the upward movement of the conical lower end 39 of the sleeve 32 to the desired closely spaced elevation above the lower end of the scribing point 4 and above opaque coating while the point 4 is in scribing relation on the sheet 2. p

The bore 33, in sleeve 32, is formed with a smaller concentric inwardly tapered lower extremity disposed in fairly close spaced surrounding relation to the chuck end of the body 21, with the interior of the lower edge of the jacket 32 in closely spaced concentric surrounding relation to the conical tip end of the point 4. The conical tip end of the jacket 32 provides a concentric suction passage 40 surrounding the conical end of the point '4, and between the lower end of the sleeve or jacket 32 and the upper surface of the coated sheet 2 when the point 4 is depressed in scribing position on the sheet 2. The suction outlet 34 may be connected by a flexible suction conduit 41 to a suitable suction, vacuum source or pump, schematically indicated at 42 in dotted lines in FIG. 1. Suction conduit 41 includes a filter trap 43 in the suction line between the scribing tool 3 and the vacuum pump 42.

The lower end of the scribing point or needle 4 is provided with a hard conical cutting tip insert 44 having a central passage 2.9a, preferably of smaller diameter than the connecting passage portion 29 for receiving slugs and debris out from the opaque coating, each time the plunger 12 is depressed. The lateral vents 31 admit air into the passage 30 to assist in lifting upwardly the slugs and debris material entering the passages 29a and 29, then into the larger passage 30 and central passage 27, where it mixes with the displaced coating material passing through the inclined passages 27a. This keeps the surface of the opaque coating surrounding the scribing point 4 clear of debris, regardless of the relative direction of movement between the point and coated sheet 2.

Briefly describing the operation of the invention, suction from the vacuum pump or source 42 will withdraw and remove any slugs and debris from the opaque coating of the transparent sheet, which are displaced during the scribing operation which enter the passages 29-29a of the scribing point or needle. While the suction within the jacket 32, surrounding the cutting point, removes and eliminates any coating debris displaced by the movement of the scribing point on the sheet 2 regardless of the direction of movement between the sheet and scribing point 4. This debris is also sucked upward between the interior of the jacket or sleeve 32 and the exterior of the,

collet chuck structure, thus keeping the surface of the sheet 2 free of cuttings and debris within the area surrounding the point at all times.

When the stylus point 3a, shown in FIG. 12, is used in place of the point 4, shown in FIGS. 1 to 6, the slugs punched out of the coating during the scribing operations are collected in the passage 45 slidably containing the slug ejector rod 46 which is yieldably urged downward by the rod spring 47. When the plunger 12 lifts the scribing point from the surface of the sheet 2, the spring 47 projects the rod 46 downward to displace the slugs from the bore 45 in the cutting tip. The suction between the tip and the jacket 32 sucks the debris and slugs upwardly out of the way to keep the surface of the sheet 2 clear and clean at all times.

FIGS. 4 and 5 also employ the same suction principle of the subject invention for the scribing point, but utilize a slightly modified form of scribing means and plunger. Therefore, similar parts, particularly on or in the scribing means or scribing stylus holder and collet structure, will be denoted by the same reference numerals as in FIGS. 1 to 3 and 11, but primed. In which figures, the rigid support of the plotter device as indicated at 1 supports an adjustable sleeve 5, in which a vertically reciprocable hollow scribing plunger 12 is mounted. The lower end of the plunger 12 is threaded internally to receive the upper threaded end 22 of the scribing needle holding chuck body 21' having a collet chuck 23 and collet sleeve 26' for securing the hollow scribing needle body 25'.

The scribing needle or point 4' is identical with the needle 4. Also, the body 21 has the similar upwardly converging suction passages 27' and 27a leading into the common larger suction passage 28'. This passage 28' extends upwardly (instead of laterally) into communication with the hollow chamber 50 of the sliding plunger 12' which carries the scribing point holder 3. The upper end of the plunger 12 is closed at 51 and has outwardly inclined suction passages 52 in communication with the hollow sleeve 5' above the plunger.

The upper interior of the sleeve 5 is threaded at 53 to receive a thread spring adjusting closure 54 having a guide passage 55 in which is mounted a lift rod 56 for raising the scribing point 4' off the coating 2 when necessary. The lower end of the rod 56 is secured in the upper end closure 51 of the plunger 12 and a coil spring 57 surrounds the rod 56 with its opposite ends impinging the top of the plunger 12' and the bottom of the adjustable closure or pressure adjusting screw 54. Adjustment of the screw 54 adjusts the downward or scribing pressure on the scribing point 4', a jam nut 58 maintaining the adjustment.

The upper portion of the barrel or sleeve 5 has a suction outlet 59 connected by a flexible suction hose 60 to I the vacuum or suction source, such as a vacuum pump like the pump 42 in FIG. 1.

The scribing operation is the same as previously referred to. Also, the suction through the scribing point 4' clears the slugs received by contact of the point with the coating 2 while the suction between the sleeve 32' and the scribing point clears the debris displaced by the point during the relative movement between the point and the coated sheet 2 in any direction.

The nut and jam nut 61 and 62 determine the adjusted position of the sleeve 5 above the coated surface 2' (with reference to the support 1').

FIGS. 8, 9 and 10 denote calibrated inserts 63, 64 and 65 which may be inserted in the barrel to vary the tension of the spring 57, Where the adjustment of the screw or plug 5 4 is not suflicient to provide the desired necessary scribing or cutting pressure of the point 4 on the coating of the sheet 2.

In FIG. 6, the same point 4, as seen in FIGS. 1 to 3 is disclosed, in which a lifting spring 66 for the plunger 12a is employed but adjusting means are provided for varying the tension on the lighter pressure scribing spring 67. The upper end of the plunger 12a is threaded in the flanged sleeve 68 with the flange calibrated at 69. Rotation of the sleeve 68 relative to the plunger 12a (held against rotation by pin and slot 70) varies the distance between the upper end of the plunger 12a and the depressible plug 71 and, consequently, the tension (compression) on the lighter spring 67. The solenoid 72 controls the depression of the plunger and scribing pointinto yieldable scribing engagement with the coating of the sheet 2..

The lower end of the plunger 12a may be calibrated as indicated at 73 to denote the position of the plunger 12a relative to the sheet 2.

In conclusion invention is not primarily in the plotter device, but in the tool or point holder and scribing means. In one form suction is employed to clear the bore of the scribing point and clear the area on the coated sheet completely surrounding the cutting point, while in the other form (FIG. 12) spring pressed plunger means are provided to clear the bore each time the point is raised above the sheet. This needle 3a, in FIG. 12, may be substituted for the needle 4 in which event the area around the point will be cleared by suction and the debris or plugs, ejected by the plunger rod 46 as the point 3a is raised, will be sucked up and eliminated by the suction surrounding the end of the point.

For purposes of exemplification, particular embodiments of the invention have been shown and described to the best understanding thereof. However, it will be apparent that changes and modifications in the arrangement and construction of the parts thereof may be resorted to without departing from the true spirit and scope of this invention as defined in the accompanying claims.

We claim:

1. In a hollow engraving point and holder for engraving opaque coated transparent sheets, a body having an axial bore and relatively movable in any direction perpendicular to said bore above said opaque coated transparent sheet, a scribing plunger axially slidable in said bore, an engraving point assembly carried by said plunger having an engraving point with an engraving tip and formed with a concentric suction passage therethrough opening inwardly through said engraving tip for receiving and removing debris and plugs from the opaque coating displaced by contacting engagement of said engraving tip with the opaque coated surface, an annular elongated sleeve-like vacuum jacket concentrically surrounding said point in closely spaced adjacent relation to said engraving tip and to the opaque coating. of the transparent sheet when said engraving tip is in engraving engagement with said opaque coating, suction means in communication with said concentric suction passage which extends through said engraving point, and in communication with the interior of vacuum jacket and said engraving point for withdrawing debris displaced from said opaque coated transparent sheet by said engraving tip in an area completely surrounding said tip during relative engraving 3 movement in any direction between the engraving tip and the opaque coated transparent sheet.

2. In an engraving stylus and holders for engraving opaque coated transparent sheets, an elongated stylus holder disposed for relative movements in any direction parallel to the opaque coated transparent sheet and movements perpendicular to the sheet into and out of engraving engagement with the sheet, said stylus holder having an axial suction passage formed therein and a lower stylus receiving and holding collet chuck portion having a central passage opening upwardly in communication with said suction passage, an elongated engraving stylus removably seated in said collet chuck portion, said stylus having a central suction conduit in communication with said suction passage opening downwardly through the engraving end of the stylus for receiving and removing debris slugs displaced from the opaque coating of said transparent sheet by contacting engagement of said stylus with said sheet, and suction conduit means formed in said holder in communication with said central suction conduit for removing said debris slugs from said stylus and holder.

3. In an engraving stylus and bolder as set forth in claim 2 an elongated sleeve-like jacket surrounding said holder and stylus in concentric spaced encircling relation to said collet chuck portion and said stylus, said jacket having an inwardly tapered lower end disposed in closely spaced concentric surrounding relation to said engraving end of the stylus, in predetermined closely spaced relation above said engraving end to form an encircling suction inlet surrounding said engraving end between said inwardly tapered lower end and the coated sheet while said engraving end is in engraving engagement with the opaque coated transparent sheet, said holder having inclined suction conduit means formed therein establishing suction communication between said central suction conduit and the space between the periphery of the collet chuck portion and the interior of said sleeve like jacket to form an annular suction inlet closely surrounding the engraving end of the stylus for removing debris displaced by said stylus in an area surrounding said engraving end during relative movement in any direction between said stylus and said opaque coated sheet while said stylus is in engraving engagement with said coated sheet.

4. In a hollow engraving point assembly, a support adapted for relative movement in a horizontal plane over an opaque coated transparent sheet to be engraved, a vertically adjustable sleeve in said support, a hollow scribing plunger vertically slidable in said sleeve, a compression spring in said sleeve urging said plunger downwardly, suction conduit means in communication with said sleeve above said plunger, an elongated cylindrical scribing point holder fixed to the "lower end of said plunger for vertical movements with the plunger having a central suction passage extending axially therethrough in communication with the interior of said sleeve, said holder having a lower concentric reduced diameter collet chuck portion formed with a bore therein for receiving a cylindrical scribing point with said bore in communication with said central suction passage, a concentric sleeve-like vacuum jacket removably mounted on said holder in surrounding contact relation thereto, sealing means between said holder and said jacket to resist air leakage therebetween, said jacket having a lower inner annular surface in concentric spaced relation to the exterior of collet chuck portion and formed with a lower extremity disposed in predetermined spaced relation below the lower extremity of the collet chuck portion forming a concentric suction inlet disposed to be positioned in predetermined closely spaced relation above the transparent coated sheet when an elongated scribing point is disposed in the collet chuck portion 'with the scribing tip thereof in scribing contact with the sheet, said holder having a suction conduit therein between said central suction passage in the holder and the annular space between the exterior of the 9 collet chuck portion and the lower interior portion of the jacket.

5. Apparatus as set forth in claim 4 including a hollow cylindrical scribing point removably fitted in said collet chuck portion having scribing tip projecting outwardly a predetermined minor distance beyond said suction inlet of said jacket to dispose said suction inlet in said jacket in predetermined spaced relation to said opaque coated transparent sheet when said scribing tip is disposed in scribing engagement with said sheet.

6. Apparatus as set forth in claim 5 in which said scribing point is formed 'with an axial suction passage therethrou'gh opening inwardly through said scribing tip, in communication with the central suction passage in said holder.

7. Apparatus as set forth in claim 6 in which said scribing point is formed with lateral suction passages therein adjacent said tip establishing communication between said axial suction passage in said point and the space intermediate the interior of said jacket and the exterior of said collet chuck portion.

References Cited UNITED STATES PATENTS 994,430 6/1911 Tunks 29 955 2,006,108 6/1935 Montuori 29 949 3,158,936 12/1964 Virta 33 1s 10 3,167,260 1/1965 Gibbons et a1. 29 955 FOREIGN PATENTS 604,904 10/1934 Germany. 958,662 5/1964 Great Britain.

HA-RRY N. HAROIAN, Primary Examiner. 

1. IN A HOLLOW ENGRAVING POINT AND HOLDER FOR ENGRAVING OPAQUE COATED TRANSPARENT SHEETS, A BODY HAVING AN AXIAL BORE AND RELATIVELY MOVABLE IN ANY DIRECTION PERPENDICULAR TO SAID BORE ABOVE SAID OPAQUE COATED TRANSPARENT SHEET, A SCRIBING PLUNGER AXIALLY SLIDABLE IN SAID BORE, AN ENGRAVING POINT ASSEMBLY CARRIED BY SAID PLUNGER HAVING AN ENGRAVING POINT WITH AN ENGRAVING TIP AND FORMED WITH A CONCENTRIC SUCTION PASSAGE THERETHROUGH OPENING INWARDLY THROUGH SAID ENGRAVING TIP FOR RECEIVING AND REMOVING DEBRIS AND PLUGS FROM THE OPAQUE COATING DISPLACED BY CONTACTING ENGAGEMENT OF SAID ENGRAVING TIP WITH THE OPAQUE COATED SURFACE, AN ANNULAR ELONGATED SLEEVE-LIKE VACUUM JACKET CONCENTRICALLY SURROUNDING SAID POINT IN CLOSELY SPACED ADJACENT RELATION TO SAID ENGRAVING TIP AND TO THE OPAQUE COATING OF THE TRANSPARENT SHEET WHEN SAID ENGRAVING TIP IS IN ENGRAVING ENGAGEMENT WITH SAID OPAQUE COATING, SUCTION MEANS IN COMMUNICATION WITH SAID CONCENTRIC SUCTION PASSAGE WHICH EXTENDS THROUGH SAID ENGRAVING POINT, AND IN COMMUNICATION WITH THE INTERIOR OF VACUUM JACKET AND SAID ENGRAVING POINT FOR WITHDRAWING DEBRIS DISPLACED FROM SAID OPAQUE COATED TRANSPARENT SHEET BY SAID ENGRAVING TIP IN AN AREA COMPLETELY SURROUNDING SAID TIP DURING RELATIVE ENGRAVING MOVEMENT IN ANY DIRECTION BETWEEN THE ENGRAVING TIP AND THE OPAQUE COATED TRANSPARENT SHEET. 